JOHN H. NORTHROP 

 TABLE VIII — Concluded. 



495 



action, noticed in Table VII, is therefore lacking here. The results 

 show that the equation gives a fairly satisfactory constant when it is 

 considered that the experimental observations are very difficult and 

 that the experiments represent changes in the value of E, x, and T 

 of many hundred per cent. Individual experiments were made which 

 gave much more constant values for K. The present series is given 

 preference, however, since it shows that the equation takes into 

 consideration changes in the enzyme concentration. It is obvious, 

 however, that this equation is merely an approximation formula which 

 will hold only under certain limited conditions and is but little 

 more general than Schiitz's rule. The derivation given offers a 

 rational interpretation of both expressions. It may be pointed out 

 also that equation (6) contains only one arbitrary constant K and 

 can therefore hardly be considered as empirical. 



DISCUSSION. 



It has been shown in the preceding paragraphs that the divergence 

 of the kinetics of pepsin action, from the results predicted from the 



